15 The four angels were freed who had been prepared for that hour and day and month and year, so that they would kill one third of mankind.
prepared for the hour, and day, and month and year – prepared by God, who alone “knows the day and hour” Matt 24:36
kill a third of mankind – this battle is not the end of man’s existence. The final destruction of man takes place when fire from heaven is sent down to destroy the earth. Here, the estimate of 1/3 is likely because the war takes place in a limited region of the world.